This invention relates to pneumatic tractor tires for use on farm tractors and similar agricultural type vehicles. Tractor tires must have good vibration characteristics on and off the road while maintaining good traction or drawbar characteristics. Such tires must also provide for the removal of soil, mud, etc., during in-field use.
U.S. Pat. No. 4,534,392 describes a prior art tractor tire known in the industry as having good traction characteristics while also exhibiting good vibration characteristics. This patented tread pattern is employed in the Goodyear Dyna Torque.RTM. Radial and the Kelly-Springfield Power Mark.RTM. L/S radial tractor tires. Each of these tires was used as prior art control tires for comparative purposes.
The present invention was employed on a tractor tire having a modified tread pattern relative to that described in U.S. Pat. No. 4,534,392. Comparative test results indicate that the tire made according to the present invention had better drawbar traction, less soil compaction, equivalent or better fuel efficiency, the same or slightly worse vibration characteristics dependent on the tractor speed when compared to the prior art control tires.
The tire made according to the present invention additionally exhibits a reduction in lug induced soil compaction. Soil compaction is considered by many a serious problem which can result in increased topsoil erosion. The tractor tire lugs compress the soil. The compressed soil is less capable of absorbing rainfall which contributes to runoff of water, which in turn leads to soil erosion. The loss of topsoil means that the productive agricultural farmland becomes less productive requiring an increase in fertilizer and chemical usage to compensate for the depleted soil.
In 1992, The Goodyear Tire & Rubber Company introduced a new tractor tire having two sets of primary and secondary lugs. The tire is commercially sold as the DT 710 and is described in U.S. Pat. No. 5,046,541. As described in the patent, this tire has good traction, vibration and cleaning characteristics. These primary and secondary lugs are shorter in length than most tractor tire lugs. The tire effectively increases the number of lugs, and, therefore, has an increase in lug surface area. This increases the performance capabilities of the tire. The flexible nature of these relative short primary and secondary lugs may also help reduce the soil compaction potential of the tire even though more lug surface area is employed.
The present invention maintains or exceeds the high performance capability of these prior art tires while at the same time greatly reducing the soil compaction potential of the tread lugs. The soil compacting surface area of the lugs is actually reduced when compared to the above referenced tractor tires.